Children's overalls, 1987 by Speattle
Kwik sew 1437 (girl) kwik sew 1439 (boy)
This is a Kwik Sew pattern. I'll update with the number when I go into the sewing room next.
It was a multi sized pattern, so I was able to make outfits for both the kids. I found coordinating fabric. The style was just about identical to that of a classic Osh Kosh pattern and I used it several times when they were small.